1. Field of the Invention
The present invention relates to a navigation device, a navigation method, a navigation program, a server device, and a navigation information distribution system.
2. Description of the Related Art
Conventionally, there has been a technology for distributing the latest map information and POI (Point Of Interest) information (hereinafter called navigation information) to a navigation device to allow the navigation device, included in a mobile body such as a vehicle and a mobile phone, to navigate the user correctly.
For example, a map publisher and a navigator manufacturer (official-information supplier) investigate the onsite road status or POI status and, if there are changes in the actual roads or POI, reflect those changes as navigation information (official data). The official data on which the changes are reflected is distributed to navigation devices.
According to this technology, the changes in the roads or POI where there are many users, such as those in the city center, are reflected on the official data relatively soon; on the other hand, it takes long from the time the status of the roads or POI in the locations, where there are few users or investigators hardly visit (for example, sparsely inhabited districts or privately owned areas), is investigated to the time the investigated result is reflected on the official data.
As an enhanced version of this technology, a system allowing a navigation device user to create (update) navigation information is proposed recently as disclosed by JP-A-2003-316686.
However, there are the following problems in the existing system.
(1) User-created information is limited to simple POI information (store and building) with no consideration for the road status.
(2) Although the reliability score of POI information can be registered in the system, this reliability score is based on the distance between a position where the user provides the POI information and the POI. That is, the user tends to give a higher reliability score if the distance between the position where the user provides the POI information and the POI is shorter. The reliability score is not calculated from various aspects such as how often the user (how many users) passed near the POI.(3) The user does not check if the navigation information is official data or user-provided data before entering a navigation processing instruction into the navigation device or giving an instruction to download data from the server. That is, there is a possibility that the user executes navigation processing on a navigation device without considering an inconvenience that might be caused by using user-provided data.